Hydroaccumulator, in a particular a bladder accumulator

ABSTRACT

A hydroaccumulator, in particular a bladder accumulator, includes a pressurized container ( 1 ) and a separation element ( 5 ) located in the container to separate a gas chamber ( 7 ) lying adjacent to an inlet on the gas side from a fluid chamber ( 9 ) lying adjacent to an inlet on the fluid side inlet ( 3 ), having a fluid connecting sleeve ( 11 ) and a valve arrangement located in the connecting sleeve ( 11 ). The valve body ( 17 ) has a transversal bore ( 33 ). The valve body is pretensioned in an open position which allows the passage of fluid and can be displaced into a closed position by a displacement of the separation element ( 5 ). The interior surface ( 15 ) of the connecting sleeve ( 11 ) lies directly against the valve body ( 17 ) and guides the displacement of the body between the open and closed positions. The side of the valve body ( 17 ′) that faces the separation element ( 5 ) is configured as a planar plate extending partially into the fluid chamber ( 9 ). The diameter of the valve body ( 17 ) is greater than its height, measured in the direction of displacement of the valve body ( 17 ). The valve arrangement has a plate-valve construction of small proportions and can be cost-effectively produced.

FIELD OF THE INVENTION

The present invention relates to a hydroaccumulator, in particular abladder accumulator, with a pressure tank and a separating elementlocated in and separating a gas space from a fluid space in the pressuretank. The gas space borders a gas-side access. The fluid space borders afluid-side access having a fluid connecting sleeve and a valvearrangement located in the connecting sleeve. The valve includes a valvebody having at least one transverse hole and is normally pretensionedinto its open position to clear the fluid passage, and can be moved intoits closed position by the displacement of the separating element. Theinside surface of the connecting sleeve for the valve body directlyadjoining the valve body forms the guide for its displacement betweenthe open position and the closed position.

BACKGROUND OF THE INVENTION

Hydraulic accumulators with valves operated by the separating elementare commercially available. In the technical reference published byMannesmann Rexroth GmbH “Hydraulic Guide Volume 1”, on page 165, abladder accumulator of this type is depicted and described. In the knownbladder accumulator, the valve arrangement comprises a seat valve. Aconical surface is formed on the end edge of a connecting sleeve facingthe fluid space to provide a stationary valve seat. The conical surfaceinteracts with a corresponding conical surface on the valve plate of themovable valve body. The valve is made similarly to the control valvesconventionally used in valve-controlled internal combustion engines,i.e., the valve plate is located on a shaft guided in a valve guide forthe valve lifting motion between the open position and closed position.The valve guide is installed in the connecting sleeve.

The disadvantage is the resulting high production costs due to therequired cost for producing and machining of a host of individual partsas a result of this known valve design. To ensure proper operation ofthe valve arrangement, the valve guide installed in the connectingsleeve must be made carefully with respect to production tolerances forboth alignment and fit. Moreover the corresponding machining of theconical surfaces which form the valve seat is necessary.

PCT/WO 00/31420 discloses a generic hydraulic accumulator with aseparating element formed from metal bellows. Within the bellows is acompression spring which keeps the separating element in thepretensioned state. On its bottom, the bellows is provided with an endplate which interacts with a valve body accommodated in the fluidconnecting sleeve of the housing of the known hydraulic accumulator andheld under spring pretension. The valve body is made as a valve lifterand is larger in dimensions in its lengthwise alignment than in thetransverse direction. Thus, the known valve body occupies considerablespace in its direction of displacement in the connecting sleeve. The endof the valve body interacting with the end plate is made dome-like. Inconjunction with the different diameters, grooves and recesses, beveledsurfaces and the transverse hole on the other end of the valve body, aresulting complex geometry requires a complex and costly machiningprocess in production. The complex geometrical structure of the closingbody continues in the area of the fluid guide. As a result of therepeated deflection of the fluid flow, especially in the area of theincident flow of the medium into the fluid space, unfavorable flowbehavior is implemented so that the known approach to hydraulicaccumulators with sensitive membrane bladders is not suitable. U.S. Pat.No. 4,068,684 discloses a generic hydraulic accumulator. In the knownapproach, the spring-loaded valve body is a sleeve-shaped plug neck witha height measured in the direction of displacement of the valve body.The height is several times larger than its diameter. The valve body isformed on its side facing the separating element as a plate. The plateis flat. Its sleeve-like outside jacket has transverse holesdiametrically opposite one another and connected to the fluid side ofthe hydraulic accumulator in the open position of the valve to carryfluid. The known valve body approach accordingly has a very largestructure in the axial direction of the hydraulic accumulator. Due tothe fluid-carrying transverse holes, the flow behavior cannot be chokedand is consequently unfavorable in the area of inflow of the medium intothe fluid space.

SUMMARY OF THE INVENTION

Objects of the present invention are to provide a hydraulic accumulatorwhere the valve body occupies little space, is geometrically simple instructure, can be economically implemented, and allows optimized flowbehavior in the area of the flow into the fluid space.

By virtue of the diameter of the valve body being larger than its heightmeasured in the direction of displacement of the valve and because therespective transverse hole in the valve piston is made as a fluidchannel, the valve arrangement is made in the manner of a plate valveoccupying little space and can be economically implemented. Therespective fluid channel is integrated into the interior of the valvebody allowing controlled triggering of the fluid flow. The fluidchannels can be chosen in terms of their number and cross-sectionalsize. As fluid passes, the desired choking takes place, with thepossibility of stipulating the damping conditions which are optimum whenthe hydraulic accumulator is in operation, depending on the intendedapplication.

By integrating the fluid channels into the interior of the valve body,complex machining for differentiated shaping of the outside surface ofthe valve body, as in the known approaches, is unnecessary. Moreover, bymeans of the respective fluid channels, a homogeneous outflow behaviorof the fluid into the fluid space is ensured. Especially when a bladderaccumulator is implemented, flow then takes place carefully around theseparating membrane which is sensitive to pressure peaks and whichordinarily is formed of a rubber-elastic material. This arrangementleads to an increased service life for the hydraulic accumulator of thepresent invention.

Production is especially simple if the valve arrangement is a slidingvalve, with the connecting sleeve being used as the valve housing andwith its circular cylindrical inside surface defining the piston borefor the valve body which is made as a sliding piston.

In these embodiments, the end edge of the piston bore of the connectingsleeve, which edge borders the fluid space, forms the control edge forclearing and closing one or more fluid channels of the sliding piston.

The piston bore which guides the sliding piston can preferably have, onits end area adjacent to the fluid space, a tapered hole section. Anannular shoulder surface is then formed, which in interaction with anopposing shoulder surface which projects radially on the sliding piston,forms a stop against which the sliding piston rests in the open positionof the valve.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses preferredembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a partial, side elevational view in section of a bladderaccumulator according to a first embodiment of the present invention,with only the part of the accumulator adjacent to the fluid-sideconnecting sleeve being illustrated and with the valve arrangementillustrated in the open position;

FIG. 2 is a side elevational view in section of only the fluidconnecting sleeve of a bladder accumulator according to a secondembodiment of the present invention, on a much larger scale compared toFIG. 1, with the valve arrangement illustrated in the closed position;and

FIG. 3 is a partial, side elevational view in section of a bladderaccumulator according to a third embodiment of the present invention onthe left side and according to a fourth embodiment of the presentinvention on the right side, with the valve arrangement being shown inthe open position.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, only the section of the pressure tank adjacent to thefluid-side access 3 is shown. The opposite end area (not shown) of thepressure tank 1 has a conventionally configured gas-side access to theinterior space of a storage bladder 5 (only schematically illustrated inFIG. 3). Storage bladder 5 forms the movable separating elementseparating the gas space 7 from the fluid space 9 in the interior of thepressure tank.

In the embodiment shown in FIG. 1, the fluid-side access 3 comprises afluid connecting sleeve 11 welded onto the end wall of the pressure tank1 adjacent to the fluid space 9. The connecting sleeve 11 is acircularly cylindrical sleeve and has an inside thread 13 on its outerfree end for the connection of a fluid line (not shown). In the end areaadjacent to the fluid space 9, the connecting sleeve 11 forms a pistonbore 15 in which a sliding piston 17 is movably guided. The connectingsleeve 11 thus forms the valve housing for a sliding valve with thesliding piston 17 used as the movable valve body and guided on theinside surface of the piston bore 15 of the connecting sleeve 11directly for its displacement along the lengthwise axis 19 of the pistonbore 15. Sliding piston 17 can be moved between the open position shownin FIGS. 1 and 3, and the closed position shown in FIG. 2.

The sliding piston 17 is pretensioned by a helical compression spring 21into the open position shown in FIGS. 1 and 3. From this position, thesliding piston can be moved with the corresponding expansion of thestorage bladder 5 against the force of the compression spring 21 intothe closed position shown in FIG. 2 when the storage bladder pressesagainst the top 23 of the accumulator sliding piston 17.

The compression spring 21 is supported with its end facing away from thesliding piston 17 on a support plate 25. The support plate adjoins ashoulder located on the adjacent end of the piston bore 15 in theconnecting sleeve 11. In the embodiment of FIG. 1, support plate 25 isheld by a retaining ring 27. In the second embodiment of FIG. 2, thesupport plate 25 is secured by a flat snap ring 29. Aside from thisdifference, the embodiment of FIG. 2 corresponds to that of FIG. 1.

The compression spring 21 is tensioned between the support plate 25 andthe sliding piston 17, and extends into an axial hole 31 in the slidingpiston 17 from its end facing away from the fluid space 9. Axial hole 31is concentric to the lengthwise axis 19, and discharges into transverseholes 33 in the sliding piston 17. These transverse holes extendradially in the vicinity of the top 23 of the sliding piston 17, and ata right angle to one another so that they intersect on the lengthwiseaxis 19. These transverse holes 33 in the sliding piston 17 form fluidchannels which interact with the valve control edge and which form thefluid access to the fluid space 9, by way of the axial hole 31 of thesliding piston 17 and the through holes 35 in the support plate 25 whenthe sliding piston is in the open position shown in FIGS. 1 and 3.

In the position of the sliding piston 17 shown in FIG. 2, the orificesof the transverse hole 33 are closed by the control edge of theconnecting sleeve 11 used as the valve housing. The control edge isformed on the sleeve upper end edge 37, see FIG. 2. As shown in FIG. 2,the piston bore 15 in its end section forms a tapered bore section withan annular shoulder surface 39. Shoulder surface 39 interacts with anopposing shoulder surface 41 on the sliding piston 17 (see FIG. 2)forming a stop limiting the displacement of the sliding piston 17 in thedirection to the fluid space 9. FIG. 1 shows the corresponding positionof the sliding piston 17 fixed by this stop.

In the two embodiments shown in FIG. 3, the support plate 25, formed asan abutment for the compression spring 21, is provided with an outsidethread and is screwed into an inside thread 13 formed in the connectingsleeve 11.

In the embodiment shown on the left side in FIG. 3, the connectingsleeve 11 in the section adjacent to the end edge 37 has an outsidethread 43 which is screwed to the corresponding inside thread of thewall of the pressure tank 1. The wall thickness of the pressure tank 1is made greater in the threaded area for this purpose.

The embodiment shown on the right side in FIG. 3 has a connecting sleeve11 which is molded on the pressure tank 1 in one piece by hot or coldforming. Otherwise, the right side embodiment does not differ from theembodiment shown on the left side in the same figure.

The invention is described above using embodiments in the form ofbladder accumulators. The invention can be equally used advantageouslyin hydraulic accumulators of a different design, for example in membraneaccumulators or piston accumulators.

While various embodiments have been chosen to illustrate the invention,it will be understood by those skilled in the art that various changesand modifications can be made therein without departing from the scopeof the invention as defined in the appended claims.

1. A hydroaccumulator, comprising: a pressure tank; a separating elementlocated in said pressure tank and separating a gas space bordering agas-side access from a fluid space bordering a fluid side access in saidpressure tank; a fluid connecting sleeve at said fluid side access, saidsleeve having an inside surface defining a piston bore with a circularcylindrical surface; a valve body in the form of a flat plate with aclosed top surface facing and engagable by said separating element, saidvalve body being a sliding piston and being slidably received and guidedfor movement within said inside surface along a longitudinal axisbetween open and closed positions, said valve body having an elongatedfirst fluid channel extending therethrough and opening on diametricallyopposite lateral surface portions of said valve body and having an axialbore opening into said fluid channel at one end thereof and on an axialside of said valve body remote from said fluid space at an opposite endthereof, said valve body having a transverse diameter in a directionperpendicular to said longitudinal axis larger than a height of saidvalve body measured along said longitudinal axis, said fluid channelopening into said fluid space in said open position and being closed bysaid connecting sleeve in said closed position; a spring in saidconnecting sleeve biasing said valve body toward said open position;tapered bore section forming an annular shoulder on an end area of saidpiston bore adjacent said fluid space; and a radially projectingshoulder surface on said sliding piston opposing said annular shoulderon said connecting sleeve and engaging said annular shoulder on saidconnecting sleeve in said open position under biasing of said spring toform a stop; whereby, said valve body can be moved by said separatingelement against biasing of said spring from said open position to saidclosed position.
 2. A hydroaccumulator according to claim 1 wherein saidseparating element is a bladder.
 3. A hydroaccumulator according toclaim 1 wherein said fluid channel has an axial length laterally boundedby internal surfaces of said valve body greater than a transversediameter of said fluid channel.
 4. A hydroaccumulator according to claim1 wherein said connecting sleeve comprises a control edge on an endthereof bordering said fluid space and closing said fluid channel insaid closed position.
 5. A hydroaccumulator according to claim 4 whereina support plate is anchored in said piston bore on a side of saidsliding piston facing away from said fluid space, said support platehaving at least on through hole, said sliding piston and said supportplate engaging opposite ends of said spring.
 6. A hydroaccumulatoraccording to claim 1 wherein numbers and size of said fluid channel andsaid axial bore in said sliding piston choke fluid flowing therethrough.7. A hydroaccumulator according to claim 5 wherein said spring is ahelical compression spring; and said axial bore is located centrally insaid sliding piston and receives said spring, said spring engaging anabutment of said sliding piston located at a juncture of said fluidchannel and said axial bore.
 8. A hydroaccumulator according to claim 3wherein said valve body comprises a second fluid channel similar to andintersecting said first fluid channel at a right angle thereto and tosaid longitudinal axis.
 9. A hydroaccumulator according to claim 1wherein said connecting sleeve is welded to said pressure tank.
 10. Ahydroaccumulator according to claim 1 wherein said connecting sleeve isformed on one end of said pressure tank in one piece by one of hot andcold forming.
 11. A hydroaccumulator according to claim 1 wherein saidconnecting sleeve has an outside thread in a section facing said fluidspace and is threadly engaged with a mating inside thread on saidpressure tank.
 12. A hydroaccumulator according to claim 5 wherein saidconnecting sleeve comprises an inside thread in a section adjoining anend of said piston bore remote from said fluid space; and said supportplate comprises an outside thread engaged with said inside thread onsaid connecting sleeve.